Hi Gnatly,
This error usually comes up when the downloaded installer file is corrupted.
If you have tried different browsers and different computers already then the only reason I could think of is the internet issues.
Are you experiencing intermittent network issues?
Try downloading the file from a different network and check.
Also try downloading from the direct download links available at: http://helpx.adobe.com/acrobat/kb/acrobat-downloads.html
Regards,
Rave